In many mobile machines, there are provided numerous wire harnesses and sensors. As machine size and complexity increases, the need for high levels of uptime and quick problem resolution becomes more and more valuable. The cost of operating machines may amount to hundreds of dollars per hour, not including operator or technician costs. Agricultural machines, such as combine harvesters are but one example of such mobile machines.
There are many potential causes of wiring failure. For example, lack of quality control at production, or wear from use or from passing over debris (such as crop material during harvesting operations, for example), poor installation techniques, etc. Any one of these may cause a degradation or failure of the control system.
Current controllers have some wiring/sensor diagnostic ability. For example, if the signal path to a sensor is broken, the controller may indicate “Error—left sensor voltage below normal”. Other examples of typical failure mode identifiers (FMI) from the SAE J1939-73 specification for defining messages to accomplish diagnostic services are identified below:                0—Data valid but above normal operation range        1—Data valid but below normal operational range        2—Data erratic, intermittent or incorrect        3—Voltage above normal, or shorted to high source        4—Voltage below normal, or shorted to low source        5—Current above normal or open circuit        6—Current below normal or grounded circuit        7—Mechanical system not responding or out of adjustment        8—Abnormal frequency or pulse width or period        9—Abnormal update rate        10—Abnormal rate of change        11—Failure code not identifiable        12—Bad intelligent device        13—Out of Calibration        
While this information is helpful in identifying the type of failure that has occurred, it is far from complete and does not specifically identity where the failure has occurred or other information that will lead to an effective resolution. Accordingly, there is a need for on-board diagnostic abilities which will both quickly and accurately identifies the failure and which is presented to the operator or technician in a way that leads to effective resolution.